In the field of color photographic light-sensitive materials, couplers which are capable of releasing a development inhibitor (DIR couplers) have been hitherto employed for the purpose of improving sharpness and color reproducibility. The improvement in color image quality using DIR couplers is marked and various kinds of DIR couplers have been developed and proposed.
One example of a DIR coupler is a coupler which is capable of releasing a development inhibitor at the coupling position as described, for example, in U.S. Pat. Nos. 3,227,554, 3,148,062, 3,933,500 and 4,477,563.
Since a development inhibitor is connected to the coupling position in this type of DIR coupler, a problem exists in that the coupling reaction of the coupler with the oxidation product of the developing agent is delayed in case of using some type of development inhibitors. In order to solve this problem, interposing a linking group between the coupling position of the coupler and the development inhibitor has been proposed. Examples of such couplers are described, for example in U.S. Pat. Nos. 4,146,396, 4,248,962 and 4,421,845. With these couplers, a certain improvement in the coupling reaction speed is observed and the performance is somewhat improved. However, it has been found that the coupling reaction speed obtained is not greatly different from that of the DIR coupler wherein a development inhibitor is directly connected to the coupling position and which has originally a high reactivity with the oxidation product of a developing agent.
Further, couplers capable of releasing a DIR coupler are described, for example, in U.S. Pat. Nos. 4,438,193 and 4,338,393, JP-A-62-291645 and JP-A-60-203943 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"). Although these couplers exhibit some degree of improvement in graininess or sharpness, further improvement is desired. In addition, with respect to color reproducibility it has been found that a problem may occur in that a dye formed upon a reaction of a DIR coupler released and diffused with the oxidation product of developing agent partially remains in the photographic material.
Moreover, other types of couplers are known and described, for example, in U.S. Pat. Nos. 4,618,571 and 4,737,451, JP-A-61-233741 and JP-A-61-238057. These couplers are one kind of DIR couplers because they release a compound which is capable of releasing a development inhibitor through an oxidation reduction reaction (DIR redox compound). These couplers exhibit excellent improvement in sharpness due to an edge effect and in color reproducibility due to an interlayer effect without the above described problems. However, these couplers are expensive to produce them and are restricted in practical use, thus further improvement has been desired.